Photographic process



e 8- G. w. w. STEVENS 2,457,005

PHOTOGRAP HIG PRQCESS Filed Aug. 1', 1 947 2 Sheets-Sheet 1 SIL VER BKOM/ODIDE EMULSION LAYER WH/L' H FM'MS GRA/Ni EMULSMN HA YIN6 HIEHJPEED /N THE BLUE To .BLUE-GREEN PORTION OF THE-SPECTRUM, AND \L/ TTLE 0!? N0 GREEN 0/? RED SENSITIVITY RED SENSITIVE LOW BLUE SPEED SILVER CHLORIDE EMULSION WHICH FORMS sumac: \l LATENT IMAGE ON THE SURFACE OF THE GRAINS JUPPORT EXPOSE TO LIGHTED COLOURED 0BJECT SHOWN AT (D Ham E, THROUGH RED FILTER EMULSION LAYER WHICH FORMS NEGATIVE fi'iA GE MOSTLY/H5105 THE JILL ER HAL/17E GRAINS EMULSION LAYER CONTAIN/N6 NEGATIVE LATENT IMAGE ON THE SURFACE 0f THE .SIL VER HAL IDE GRAINS SUPPORT EXPOE T0 LIGHTED COLOURED OEJEET SHOWN AT ABOVE, THROUGH BLUE FILTER, JUST SUFFICIENT T0 EXPOSE THE UPPER LAYER, BUT INSUI'F/CIENT T0 AFFECT THE LOWER LATER MAG'E M057 INSIDE THE SILVER HAL/DE GRAINS /EMUL5ION LAYER C ONT/1 ININ6 NEGATIVE LAT EN T EMuLs/oN LAYER CONT/1 IN/NE NEGATIVE LATENT IMAGE ON THE Jl/RmcE 0! THE J/L VER HALIDE GRAINS .SU/IORT IMMERSE Bum-710E" DEVELOPER 71-)KJP ATTOR EYS' LHTEN T IMAGE MOJTLY INSIDE THE SILVER HAL IDE Dec. 21, 1948. G, w. w. STEVENS 2,457,005

PHOTOGRAPHIC PROCESS Filed Aug. 1, 1947 2 Sheets-Sheet 2 mun/mum? com/mm NEGATIVEMTENT MAG! Momr ms/ps ms mm mu: GM/NS AND 04mm: JFFORH/NG JUKFACELATENT ma:

EMULS ION LAYER CONTAIN/N6 NEGATIVE LATENT lMA'E ON THE J'l/REALE OF THE S/LVER HAL/PE G'MINS EXFOSE UNIFORMLY THROUGH BLUE FILTER EMl/LSMN LAYER CONMIN/NG/VEGATIVE LATENT IMAGE MOSTLY INSIDE THE J/L VER HAL/DE GRAINS AND REVERSED Ln TENT IMAGE ON THE .Sl/RFACE of 7745 SILVER HAL/PE GRAINS EMULSION LAYER CONTAIN/N6 NEGATIVE LATENT IMAGE ON THE JURFACE 0F THE .S/L VER HAL/PE GRAINS SUPPORT DEVELOP IN SURF/1:5" DEVELOPER WATER/AL F/i'OM Wfl/(HA PRINT OF ONLY THE V'OLUE PORTION OF ORIGIN/PL CAN BE MADE SUPPORT GUYWJLLLIM WILLIS STEVENS INVENTOR h-A -f ATTOR EYS Patented Dec. 21, 1948 PHOTOGRAPHIC PROCESS Guy William Willis Stevens, Harrow, Wealdstone,

England, assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application August 1, 1947, Serial No. 765,635

In Great Britain January 31, 1945 6 Claims.

This invention relates to photographic proc esses and tomaterial therefor.

In the copending application of Edward B. Knott and Guy W. W. Stevens, Serial Number 765,636, filed August 1, 1947, there is described a method for selectively producing images in a photographic material comprising an inseparable combination of silver salt emulsions on a single support which comprises employing two emulsions of different types (type I-an emulsion which forms the latent image mostly inside the silver salt grains; and type II-an emulsion which forms surface latent image on the silver salt grains)','selectively exposing (simultaneously or consecutively) both emulsions to form latent images therein, and then differentially developing the latent images so formed.

In the copending application of Edward B. Knott and Guy W. W. Stevens, Serial Number 765,632, filed August 1, 1947, there is described a method for producing a reversed photographic image, which comprises exposing to an object or image a sensitive layer comprising a silver salt emulsion of the aforesaid type I (an emulsion which forms the latent image mostly inside the silver salt grains), then, without developing the latent image so formed to a visible image, treating the emulsion to render it capable of forming surface latent image, and then subjecting it directly (i. e. not through a negative-or positive image) to an exposure of sufficient intensity and time to cause a reversed image to develop upon treating the directly exposed emulsion in a developer which will develop surface latent images, but not" develop or develop only slightly the firstformed internal latent image.

I have now found that this forms the subject of the present invention that very useful results can be obtained, if in the inseparable combination of silver salt emulsions described in the said copending application Serial Number 765,636, the type I emulsion (an emulsion which forms the latent imagemostly inside thesilver salt grains) is processed to -give a reversed image according to the method described in said copending application Serial Number 765,632, and the type II emulsion (an emulsion which forms surface latent image on the silver salt grains) is processed to give an ordinary image. In a modification of this invention, the type II emulsion is processed by known reversal technique and, the type I emulsion is processed to give an ordinary image. In a preferred form of the invention, the emulsions have different spectral sensitivities and therefore they can be selectively exposed to form the said latent images therein bydliferent coloured lights; such exposures can, of course, with advantage be made simultaneously but this is not essential.

Ifdesirecl a filter layer may be interposed 'be-" tween the two emulsion layers to facilitate the selective exposure thereof. For instance, if a yellow filter layer is interposed, the emulsions can be exposed from opposite sides by means of blue light; this method is useful when printing from two difierent black and white colour separation rccords. In many cases it 'is better to use an interposed filter layer and at the same time use emulsions of different colour sensi-. tivities. For example if a yellow filter layeris used and the one emulsion is dye sensitised'to red then on exposing the material (from the side remote from such red sensitive emulsion). to.

blue and red images simultaneously, the blue image will be recorded in the nearest emulsion and the red image in the other emulsion.

In either form of the present invention there is obtained in one of the two emulsions, a reversed image and in the other of the two emulsions an ordinary (i anon-reversed) image.

In the above described form of the invention where the image in the type I emulsion is 'p'rocessed to give a reversed image according to the method described in application No. "765,632 and the type II emulsion is processed to give anordinary image, then if desired, after both images have been developedthey may both be reversed by known reversal technique.

The method of the present invention 'is very useful when applied to the production of colour corrected colour photographs, that is to'say,

where the so-called masking method of colour correction is employed. In such masking methods as applied to reproduction of a multicoloured object or image, one colour separation record in the form of a negative is printed through a positive transparency of another colour separation record; such positive is of lower overall contrast than the negative, and is known-as a mask. The function and method of using such a mask is well known. It haspreviously been suggested to make the negative and its mask in register on 'a single support using in superimposition an ordinary emulsion in which the negative is formed and a special emulsion in which the positive is formed as a reversed image on direct development; such direct positive was developed as the result of a positive latent image being firstformedby solarization, In the method of the present invention, howhighly sensitive emulsions being used, and does not involve any difiicult treatments such'as controlled penetration for selectively processing the" superimposed or mixed emulsions.

The following is an illustration of how the present invention is applied to" such masking technique. On a glass support, there is first coated an emulsion, for instance a gelatinosilver-chloride emulsion of type II (a gelatinosilver-chloride emulsion latent image on the silver halide grains) which is dye-sensitized to thered; and over this emulsion and: indirect contact therewith is coated agela'tin'e-silveflhalide" emulsion of type I (agelatinosilver-halide emulsion which forms the latent image mostly inside the silver halide grains) which is not dy'esensitized, either to red or to green. The sensiti'v'e material so obtained is then exposed to a multi-colored object or image through either a red'a-nd bluefilter 'suo'cessively'or throughasingle filter transmitting; both red and blue; The" type I- emulsion is mad'eito have a sufiicie'ntly high speed to'insurekthatthe amount of blue light necessary for its co'rrectex'posure, is too small to have'any practical'effect on the type Illemulsion. Hence; the red'expos'ure'affect's only the type II emulsion and the blue exposure only the type I einulsion. The exposed material is then immersed in a surface developer (adeveloper which develops substantially only surface latent image) and givena .un'ifor-m blue light'exposure just sufficient to f'orm'in the type'I-em'ub sion' a reversed latent image, but i-nsuifi'ci'entto have anypractical effect on: the: type I I 'emuI- sion; The materialis held' in this developeruntil the negative image (i. 'e; the red record) is-sa-tis-- factorily developed inthe type II emulsion and during this time a positive-image" (i; e. the-blue record) develops inthe type" I emulsion;

The -said uniform exposure should be made from the side remote from the type I-I"eh1ulsion, sothat it is notinfiuenced by the negative image developingupin the type II'em-ulsi'on. Some convenient control of contrast of the positive'image' can be obtained by giving the uniformexposure at-asuitable time'after immersion of the i'nateriai in the surface developer;

is almost wholly developed, quitea low contrast- Will be-obtainedin the said positive image by the time the negative image iswholly developed.

Inthe processing technique just described, there -is-obtained anegative imagein the type II emulsion and a positive in the type I emulsion. An advantage given by the-present invention is that=insteadof processingsuch anexposed--ma ter-ial in-that way, it can be processed to give a--positive image inthe type II emulsion and a negative image in-the type-I emulsion. For in stance, this-canbe done by omitting to give the material-a uniform exposure when developing the first-formed negative-latent image-inthe'type II emulsion, andthen, after suchnegative image is developed (there being no developmentsofar' of the type I- emulsion-) dissolve outall the: silverof -s'uch image with a bath which does not destroy which forms surface for instance, if such exposure is given when the said negativeimage I cedures 'are-giv'enWith reference to the particular material-given above, it is tob'e understood that the red-sensitivity of the type II emulsion, nor destroys the internal image of the type I emulsion. Next give a uniform red light exposure to the material preferably from the side remote from the type I emulsion, and then immerse the material in an internal developer (a developer which develops latent image inside the silver salt grains) whereupon a positive image develops in the type II emulsion and a negative image in the type I emulsion. Where the type I emulsion is more stable to fogging developers than is the type II emulsion, as is especially the case when the type: I]? emulsion" is a silver chloride emulsion, the following alternative procedure can be adopted. The said uniform red light exposure is omitted and thenonly the type I emulsion develops in the internal developer; after this step, the material is treated with a fogging developer which will rapidly develop the residue of the type II emulsion Without effecting the silver halide remaining in the type I emulsion.-

Still another way of processing the material.

consists in -treating it (after the exposure to the multi-coloured object or image) in a surfaceimage), and give a uniform exposure (which maybe" blue) was to fog the-remaining silver'halide of the type II emulsion and develop this "only in" a surface developer.

It will be seen that in some of the cases illustrated'above, the same material-and same image exposure (i; e: the first exposure) can 'be used to give at will either a positive of the one colour record-and a negative of the other or vice versa.

Although the above described processing proanalogous procedures can be applied't'o material with colour sensitivities different from those given above. Thusinsome cases it may be convenient to'employ' a type I emulsion having a relatively low speed inthe blue to blue-green portion of the'spectrum but dyes'ensiti'se'd to red and atype II emulsion having arelatively high speed in the blue to blue-green portion of the spectrum. Alternatively, if instead of recording red and blue respectively in the twoemulsions, i'tis desired to record green and blue respectively, then instead of the type II emulsion being sensitised in well known manner tor'ed and not green, as indicated above, itc'an be sensitised to green and not to red; the subsequent exposure to a m'ulti-coloured object will then; of course, be to green and blue light. V

Another use 'to' which the method of the present invention can be put is in-the selective recording of coloured parts of a multi-coloured record, For

instance, if a map, or other drawing consists of say red-lines, blue' lines, magenta lines and black lines, then a record of only the blue lines for exairiplefi can be easily obtained. One way in' support, such as a glass" plate was coated I first with a contrasty, low blue speed gelatinc-sil'-- ver-chloride emulsion (type II) sensitized to the red with 0.15 g. of 3,3-dimethy1 9-ethy1- i,5,4 ,5 dibenzothiacarbocyanine iodide, the carbocya'nine dye being added to an amount of the emulsion containing 165 g. of silver chloride, to give an emulsion layer containing 0.4 g. of silver per square foot. This emulsion layer was then coated with a type I gelatino-silver bromiodide emulsion of high speed (relative to the type II emulsion) in the blueto blue-green portion of the spectrum and having little or no green or red sensitivity to I give an emulsion layer containing 0.9 g. of silver per square foot superimposed on the first emulsion layer.

The resulting sensitive photographic plate was then exposed to a drawing, such as a map, com- 6 Upon exposing the'two-layer element to uniform blue light, the upper emulsion layer forms reversed latent image on the surface of the silver halide grains as shown at F (second sheet or: drawings). Upon developing the'two-layer ele--' ment in the"surface developer, the reversed latent image in the upper layer and the negative I latent image in the lower layer develops as shown 1 at q. Thus, there is obtained a material in which only the record of the blue portion of the From this original object is substantially clear. material a positive print of only the original blue portion can be made.

It will be observed that although a straightfor- 151 ward photograph taken on any ordinary emulsion posed of blue, red, green and black lines, first through a red filter (Wratten No. and then through a blue filter (Wratten No. 47A), the

latter exposure being carefully made so as to give just sufficient exposure to the type I emulsion, but insufficient to affect the type II emulsion. In'the present instance, the drawing or map was illuminated with white light by means of a 500 candle-power tungsten lamp at two feet'away and the sensitive material exposed in a camera, the

exposure time being 3 minutes for the red filter and 10 seconds for the blue filter.

The exposed plate was then immersed in the following surface developer solution at 70 F.

N-methyl-p-aminophenol sulfate grams 1.1 Sodium sulfite (anhy.) do -37.5 Hydroquinone do 8.5 Sodium carbonate (anhy.) do 32.5 Potassium bromide do 1.4 Water to make cc 1,000

After seconds immersion in this developer solution, the plate was given a uniform exposure for 10 seconds to an ordinary 40-watt electric lamp at 5 feet distance through a blue filter (Wratten 47A). Development was then continued for a total of 4 minutes. The contrasts obtained in the resulting negative and positive images were for all practical purposes the same and only the record of the blue lines was substantially clear in both images. Hence by printing from the finished material, a positive print of only the original blue lines can be made.

The accompanying drawings show a flow-diagram which depicts graphically the process described in the foregoing example. In the first sheet of drawings at B is shown a support coated red sensitivity. Upon exposure of the two-layer element shown at B to the lighted coloured object shown at A through a red filter, negative latent image is formed on the surface of the silver halide grains in the lower layer as shown at 0. Upon then exposing the two-layer .element to the coloured object shown at A through a blue filter negative latent image is formed mostly inside the silver halide grains in the upper layer as shown at D. Upon then immersing the two-layer element in a surface developer, that part of the} upper emulsion layer which does not contain negative latent image is rendered capable of forming surface latent image asshowlrat E.

layer through a minu blue filter in known manner will selectively record the blue, it will also record black lineswhereas the method illustrated in the foregoing example records the blue lines ;but not the black lines nor any red or greenlines, Y i. e. lines absorbing blue and reflecting red or.

green. Thus where black lines cross blue lines in the original, there result gaps in the blue lines on the final print obtained as above. The reason -;that the record of the blue lines is the only clear portion common to both said images is that the negative image (1. e. the red record) is clear only where the red is entirely absent (i. e. where red is not reflected, for instance, where there are blue I ;and black lines) and the positive image (1. e, the

blue record) is clear only where blue is present (i, e. where blue is reflected, for instance where there are blue lines, magenta lines and white" areas). Where I refer to a part of an image tbeing clear, I mean only that that part is very much more transparent than the remainder of the image.

Emulsions of type I, i. e. photographic silver salt emulsions which form the latent image mostly ,;inside the silver salt grains have found little or no commercial use heretofore, in fact they have for a long time been considered as practically useless. Burtons emulsion given in Walls Photographic Emulsions, 1929, pp. 52 to .53. This type .of

emulsion can be prepared in other known manners, for instance by taking an ordinary gelatinosi1ver-bro1niodide emulsion containing between.

An example of such type of emulsion is 0.5 per cent and 5 per cent silver iodide (based on the total silver halide) and coating the emul- 1.

sion as a layer and then after drying, treating the emulsion with the following bath:

Potassium dichromate grams l2 Conc. sulfuric acid cc Water cc 1,000

The time of treatment must be sufiicient to inhibit,

surface latent image formation as can be easily ascertained by exposing (after washing) and then given below.

as desired.

The emulsions employed in the instant invention'z-are characterized by their behavior in sur' face and internal developers. Such developers are given below under Formulas I, II (a), II (b) and III:

FORMULA I 7 Surface developer p-Hy'droxyphenylglycine grams 10 i Sodium. carbonate (crystalline). do Water to; do- 1,000 '1 Development time 4 minutes at 20 I ,treating with developers of Formulas I and III, Such an emulsion can then be-used as it is or may be remelted and coated againerroneous v Formosa II"'(a,);

Internal. developer Hydroquinone: gnams; N-methyi' p-aminophenol; sulfate: do 15."; sodmmxsulfite (anhydrous) do- .l 50 Potassium bromide ,do'- 10; Sodium hydroxide do- 25,? Sodium. thiosulfate (crystalline), do 20.. Water" to cc.'..

Developmenttime- 3'minut'es at --"C.

FORMULA II" (11) internal. developer Hydroquinone- "grams" 12" 16v: N'- methyl -p'-amin'ophenol-' sulfate do; 3 sodium-sulfite (crystalline)-; do; 90 Potassium bromide "doe-" Sodium carbonate (crystalline) do; 150 Sodium thiosulfate (crystalline) ae Water tocc-' 1,000'" Development time 4 minutes at 120C) FORMULA: III

Commercial developer Ifhis isthe sameas Formula II (b) butomittin'g. the sodium thiosulfate.

FldrmulaII (a) isa more energetic developer. than Formulav II (b) so that it. usuallyogives-lav higher. effective. speed and a higher contrast. than.F,'0rm,ula II. (b) but. is. often.=not. so,.con-' venient, since it. hasv ahigher tendency to. aeriall'. oxidation. and to. give fog.

While in. this specification. weihave. described. our inventionpartly. in regard to a theory of. in..- ternal and surface latent images, the correctnesa. or otherwise of such theory, is not essential to the-successful working of the invention, it being only necessary to.choose the. emulsionsaccording, to, the tests hereinafter given.

The; present invention. employs the following; types of emulsions:

TYPE I These are the emulsions which will develop (after exposure to light) in internal developers" oi'thekind' given in at least" one of Formulae II (a): and- II (b), but will not develop or only slightly develop in Formula III or in Formula I; i. g2, thesurface developers.

(1) Normal range. of exposures As measured according to normal photographic testing technique, when a test layer of. thatype I emulsion is coated on a transparent support (e. g. glass) and the layer is exposed to a light intensity scale the whole of which is e)?- posed for'some fixedtime between and 1' sec'-' ond andis developed in the internal developer" Il."(a): the transmitted density obtained at any point-along the logmE axis over a'--range-of 310 starting from the threshold of the curve (D=0.1 above fog) should be at least 5 times, and" preferably atleast 10 times the transmitted density'obtained when an identical test layer of the emulsion is developed with the surface developer of F'ormula'l or III, the measurements of density-v being made at the corresponding (i. e. the same)- points of the logmE axis:

(2) SmaZZ..1-.ange of exposures .For this purpose the emulsion. need not con.- form to'such a"regidrequirement; for instance 1' for'makinga tone correctingmask, but itissufll-. cient if in-theabove" test the upper *limit"'of"3il" is substituted-by an upper limit off-Lo.

These-are. the :emulsionswhich. whenexposed to axlight intensity, scale, the whole of which is exposed-for some, fixed time between 100 and 1 second,-. will develop. normally inFormulaeI and.

IIL-asWell asin Formulae II (a) and II (b). As measured accordingsto normal photographic test-- ingrtechnique; when,a-'-test layer of the emulsion ,islcoatedtorrlatransparent support (e. g. g ass).-

anda-thezlayerl isexposedto alight intensity scale tbawhole of .Whichds exposedfor some fixed time betweenJ/mo and lsecond and .istdeveloped in the internal developer II (b), the transmitteddensitv obtainedtatany point along thelogmE-axis of the curverbetween therange of 0 to3.0 and preferably betweenlthe range ot-O to.-2.0-.does.not exceed the transmitted. density obtained when an identical; test layer-of the emulsion is developed in Formula:

,III, themeasurements-of densitybeing made at "the same pointshon the log-mEaxis of the curve.

Since Formula-III contains sodium sulphite and.

Formulail is freefrom. sulphite,v and sulphite isknown to have. some solventflaction on. silver- ,chloride. and, bromide. (although very little on silver iodide), it is a-pparent that when. testing an: emulsion to, obtain,- with a high degree" of precision, information ontheamountof surface latent image. .givenby; such emulsion, it isimpor-tant to use Formula I; Nevertheless. where, as will be apparent hereinafter, in performing the invention a small-'amountof development, of the internal latentimage-is of-no real consequence for practical"purposesfltmay'loe advisable to employ" FormulaIII; j since this" developer is not only less liable to aerial 'oxidation'but gives better density in the image'produced'by'the development of the type II emulsion;

It is torbemoted: that an.

,necessarily'capable of developing-not .only alatent at..20.? C. in thefollowing. developer, (Ila):

Hydroquinione'i grams 15: N methylep-aminophenolsulphate do 15 Sodiunrsu'lphite;anhydrous; do; 10

=--Potassium bromide; do- 10 Sodiumrhydroxide: do' 25 Sodium thiosulphate,. crystalsdo' 20 Waterto cc- 1,000

image; inside grains-but also-of developing a latent image onwthe surfacerofr. grains (whether such grainsicontainl internal latentimageor not) and' alsoiof canrying onathe development of a surface. ,latent: images: which'has previously been 1 only one. of said,emulsions-being-a light-sensitive silver salt. emulsion-(I) atest layer of which coated upon altransparent glass support upon exposure to; allight intensityr scale for a fixed time between 1 and. lrsecond and development for 3 minutesgives 'a trarrsmitted 'density at: any point along the "log-loEfaxi's; over-a range of ltO starting from the internal? developer is;

threshold of the characteristic curve beginning at a density of 0.1 above fog, at least times the transmitted density obtained when an identical test layer of the emulsion is developed for 4 minutes at 20 C, in the following developer (I) p-Hydroxyphenylglycine grams 'Sodium carbonate, crystals do L100 Waterto ccl. [1,000

the measurements of density being made at the same points on the logioE axis, and the other of said emulsions being a light-sensitive silver salt emulsion (II) a test layer of which coated on ,a transparent glass support upon exposure to a light intensity scale for a fixed time "between- 71m and 1 second and development 'for'4 minutesa't 20" 0. in the following developer (IIb):

gives a transmitted density at any point along the 10gl0E axis of the curve between the range of O to 2.0 which does not exceed the transmitted density obtained when an identical test layer of the emulsion (II) is developed for 4 minutes at 20 C. in

the following developer (III) Hydroquinone grams; 12 N-methyl-p-aminophenolsulphate do I, 3 Sodium sulphite, crystals do '90 Potassium bromide do 4 Sodium carbonate, crystals do 150 Water to cc; 1,000

the measurements of density being m ade at the same points on the logmE axis of thec urve,;comprising selectively exposing bothemulsions to a lighted object or image to form latentimage in both emulsions, treating the photographic material to render the emulsion (I) capable of forming latent image developable by the aforesaid developer (III), then uniformly exposing to light the photographic material to produce latent imagelin emulsion (I) some of which is developable'by the aforesaid developer (III), said uniform exposure to light being insufficient to have any practical efiect on said emulsion (II), then developing the photographic material in a developer .whichdevelops the latent image developabl e by said developer (Ill) and gives no more than a negligible development of the negative latent image formed by the original exposure in emulsion (I) "compared with the positive image which is developed insaid emul ion (I).

2. The method of selectively producing images in a photographic material comprising, inseparably combined and extending over the same area on a single support, two photographic emulsions, one of said emulsions being a light-sensitive silver salt emulsion (I) a test layer of which coated upon a transparent glass support upon exposure to a light intensity scale for a fixed time between W10 and 1 second and development for 3 minutes at 20 C. in the following developer '(IIa):

Hydroquinone l grams 7 l5 N--methyI-p-aminophenol sulphate do Sodium sulphite, anhydrous do -10 Potassium bromide do 10 Sodium hydroxide do =25 Sodium thiosulphate, crystals do Water to l; cc 1,000

gives a transmitted density at any point along the logioE axis, over a range of 3.0 startingfrom'the threshold of the characteristic curve beginning at a density of 0.1 above fog, at least 5 times thetransmitted density obtained when an identical test layer of the emulsion is developed for 4 minutes at 20 C. in. the following developer (I) the'ineasurements of density being made at the same points on the logmE axis, and the other of said emulsions being a light-sensitive silver salt emulsion (II) a test layer of which coated on a transparent glass support upon exposure to a light-intensity scale for a fixed time between 400 "and 1* second and development for 4 minutes at I 20 -'C.' in the following developer (IIb) givesatransinitted density-at any point along the logmE axis of the curve between the range of O to 2,0 which does not exceed the transmitted dehsi r obtained when an identical test layer of the emms oa (II) is developed, for 4 minutes at-"2O L" C. in the following developer (III) I-Iydroquinone grams 12 N-Inethyl-pj aminophenol sulphate do 3 Sodium sulphite, crystals d0 Potassium bromide s do 4 sodiumucarbonatey crystals do; .150 lli ater to 's, 'cc 1,000

the measurements of densitybeing made at 'the same points on the logmE axis of the curve, comprising selectively exposing both emulsions to a lighted objec t or image to form latent image in both?v 'emulsions',,treating the photographic mate'- rialtorerider the emulsion (I) capable of forming latent image develop'able by the aforesaid developeif 'dli), then "unif ormlyexposing to light c material to produce latent A M nf(I) some of which is developable' by aforesaid developer (III), said uniform) exposure to light'being insufficient to have any practical f'eflect on said emulsion (II) then developing use photographic material in a developerwhich develops the latent image developableby saiddeveloper III) and gives'no more 'than fa"11egligi.ble development of 'the negative aten mage-remain the original exposure in emulsion (I) compared with the positive image which is developed in said emulsion (I);

-- -3. The method-of selectively producing images in 'a photographic material comprising,- inseparably combined and extending over the same area on a single support, two photographic emulsions, one of said emulsions-beinga light-sensitive silver halide emulsion (I) a test layer of whicli' coated upon: a transparent glass support upon exposure to a light intensity scale for a fixedtiiiie between l/looand 1 second and develo pment'ior 3j niiiputes at 201 c. in the following deve oper (IIa) :j

gives a transmitted at point along ease-nos ithe logmE axis, over a range of 8.0 starting-from,

-:the.threshold.of the characteristic curve beginning at a density-of 01 above fog, atpleastfi times :thertransmitted density-obtained when an identtical test layerof the emulsion is developed for -j A minutes at 20 C. in the following developer (I) ,p+I-I ydroxyphenylglycine grams Sodium carbonate, crystals do 100 "Water to cc' 1,000

*I-Iydroo uinone grams 2 N -methyl-p aminophenol sulphate 'do 3 #Sodiumeulphite, crystals 'do 90 Potassiumbromide do 4 "Sodium carbonate, crystals -do 150 ESO'Clllllll thijosulphate, crystals do 20 Water to ccs 1,000

:gives .a transmitted density at any point along the logmE axis of the curve between the range of 0 to 2.0 which does not-exceed the transmitted density obtained when an identical test layer of the emulsion '(II) is developed for 4 minutes at .20 C. in the following developer (III) Hydroquinone grams 12 N methyl p aminophenol suphate d'o 3 Sodium sulphite, crystals do 90 Potassium bromide do 4 Sodium carbonate, crystals do 150 Water to cc 1,000

the measurements of density being made at the samev points on the loglOE axis of the curve, comprising selectively exposing both emulsions to a lighted objector image to form latent image in wbothemul'sions, treating the photographic material to render the emulsion (I) capable of forming latent image developable by the aforesaid developer (III) ,lthen uniformly exposing to light the photographic material to produce latent image in emulsion (I) some'of which is developableby the aforesaid developer (III) said. uniform .exposureto light being insufiicient to have any practical efiect on said emulsion (II), then deyelopingthe photographic material in a developer which develops the latent image developable by said developer (III) and gives no more than a negligible development of the negative latent image formed by the original exposure in emulsion (I) compared with the positive image which is developed insaid emulsion (I).

4. The method of selectively producing images in a photographic material comprising, in separably combinedand extending over the same area on a single support, two photographic emulsions, ,Qne of said emulsions being a light-sensitive silver halide emulsion (I) :a test layer of which coated upon a transparent glass support upon exposure to a light intensity scalefor a fixed time between /100 and 1 second and development'for 3lminutes at 20 C. in the followin developer (IIa) Hydroquinone grams 15 N methyl-p-aminophenol sulphate do 15 Sodiumsulphite, anhydrous do 10 12 :iPotassium Joromide ll srams. 10 Sodium hydroxide d0- l 25 ,Sodium thiosulphate, .-crystals ,l do In 20 -Water to L e C. L000 gives a transmitteddensity at any pointalong the logioE axis, over a range of 3'.0 starti lj l.from the threshold of the characteristic curve beginning at a density of'0;1' above fog; at'le'astlo'ti'mes the transmitted density obtained when =-an-=identical test layer of the emulsion is developedior 4 minutes at 20 p-Hydroxyphenylglycine l gramS- I0 :Sodium carbonate, crystals", do-a."- I00 Water to I V cc;,,1()00 the measurements of density -being-made"-a-t"the same "points on the logmE-axis, and 'the'other of said emulsions being a light-sensitive silver halide emulsion (II) a test layer of=which coated on a transparent glass support uponexposure' to a light intensity scale for a fixed time between /100 and 1 second and-development for 4min- -utes at 20 C. in the followingdeveloper (I111):

Hydroquinone l g r am s 12 .Nmethyl p-aminopheno1 sulphatewdoufl (3 Sodium sulphite, crystals do s Potassium bromide ,do Sodium carbonate, crystals l.,do .150 Sodium thiosulphate, -crystals ,do -20 Water to cc, .l,00 0

gives a transmitted density at any point along the logioE axis of the-curve betweenthe range of '0 to 2.0 which does not exceed the transmitted density obtained when an identical test layer of theemulsion (II) is developed for l-minutes at 20 C. in the following developer (III):

Hydroquinone grams l2 ,N-methyl-p-aminophenol sulphate do ;3 Sodium sulphite, crystals do 90 Potassium bromide -do a -41 .Sodium carbonate, crystals do .150 Water to l cosh-1,000

,the measurements of density'being made atthe ,same points on the logloE axis of the curve, com prising selectively exposing both emulsions to a lighted object or image to iormjglatent image in both emulsions, treating the photographic material to render the emulsion (I) capable of forming latent image ldevelopable by the'aforesaidldeveloper (III), then uniformly exposing'to light the photographic material to produce latent image in emulsion (I) some of which isldevelop- ,able by the aforesaid developer (III) ,said unform exposure to light being insunicent to have any practicalefiect on said emulsion (II), then developing the photographiamaterialin a;deve1oper which develops the latent image developable by said developer (III) and gives no more than ,a (negligible development of the negative -latent image formedby theoriginal exposure in :emulsion (I) compared with thepositive image which .is developed in said emulsion (I).

5. The method of selectivelyvproducingaimages in a photographic material comprising, inseparably combined and extendingi-overthe samevarea on a single support, two photographicl-emulsions, one of said. emulsions being a lightesensitive silver halide emulsion (I) a test layer of which coated ,upon. a itransparent glass support upon exposure ,toia light intensity scalefora fixed time between "C. in the following developer /100 and 1 second and development for 4 minutes at 20 C. in the following developer (IIb):

Hydroquinone ..grams 12 N-methyl-p-aminophenol sulphate do 3 Sodium sulphite, crystals do 90 Potassium bromide do 4 Sodium carbonate, crystals do 150 Sodium thiosulphate, crystals do 20 Water in cc 1,000

gives a transmitted density at any point along the logmE axis, over a range of 3.0 starting from the threshold of the characteristic curve beginning at a density of 0.1 above fog, at least times the transmitted density obtained when an identical test layer of the emulsion is developed for 4 minutes at 20 C. in the following developer (III):

Hydroquinone grams 12 N-methyl-p-aminophenol sulphate do 3 Sodium sulphite, crystals do 90 Potassium bromide do 4 Sodium carbonate, crystals do 150 Water to "cc..- 1,000

the measurements of density bein made at the same points along the logioE axis, and the other of said emulsions being a light-sensitive silver halide emulsion (II) a test layer of which coated on a transparent glass support upon exposure to a light intensity scale for a fixed time between /100 and 1 second and development for 4 minutes at 20 C. in the aforesaid developer (111)) gives a transmitted density at any point along p-Hydroxyphenylglycine grams 10 Sodium carbonate, crystals do Water to cc 1,000

then uniformly exposing to light the photographic material to produce latent image in emulsion (I) some of which is developable by the aforesaid developer (I), said uniform exposure to light being insuflicient to have any practical effect on said emulsion (II), then developing the photographic material in a developer which develops the latent image which is developable by the aforesaid developer (I) and gives no more than a negligible development of the negative latent image formed by the original exposure in emulsion (I) compared with the positive image which is developed in said emulsion (I).

6. The process according to claim 5 wherein the two emulsions (I) and (II) are differentially colorsensitized.

GUY WILLIAM WILLIS STEVENS.

No references cited.

Certificate of Correction Patent No. 2,457,005. December 21, 1948.

GUY WILLIAM WILLIS STEVENS It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 37, for the word that read and; column 6, line 74, Formula 1, for Water to -do- 1,000 read Water to cc 1,000; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 24th day of May, A. D. 1949.

THOMAS F. MURPHY,

Assistant Oommissioner of Patents. 

